Theory of Raft Interactions in Ternary Colloidal Membranes*

Colloidal membranes are a recently developed experimental system in which depletion
interactions drive rod-like chiral particles to self-assemble into one rod-length- thick monolayers
of vertically aligned rods. This talk will discuss the theoretical analysis of colloidal membranes
comprised of three rod species: one with a short length and right-handed chirality, the other
two with long lengths and respectively right- and left-handed chirality. Experiments have shown
that such a system exhibits a rich phase behavior, including microphase separation with the
short rods forming finite-sized domains floating in a background of the two long species. Tuning
the background composition to be effectively achiral leads to complex, non-pairwise interactions
and attractions between domains. We employ a Ginzburg-Landau description of the system to
understand how this behavior arises from on a combination of chirality, rod length mismatches,
and the depletion interactions.